Call termination, also known as voice termination, refers to the routing of telephone calls from one telephone company, also known as a carrier or provider, to another.
The terminating point is the called party or end point. The originating point is the calling party who initiates the call.
Traditional Telecommunication Network (TTN) is a network which uses technologies such as: GSM, CDMA, WCDMA, PSTN etc. and does not use a VoIP technology for its last hop voice communication to the end user device.
These networks usually use E.164 numbering format to represent the user identity (e.g. 18092005151)
Traditional Terminal Application (TTA) is a terminal application capable of receiving calls on traditional telecommunications networks (TTN).
OTT is an acronym standing for over-the-top, covering a wide range of content delivered through applications and third-party services which are independent of the underlying communication infrastructure technology. OTT is usually used to describe applications that use the Telecommunications Service Provider (TSP) infrastructure to provide services and applications to its network subscribers competing sometimes with the traditional TSP's services. Over-the-top content can be accessed directly through an Internet-connected platform such as a PC, laptop, tablet, smartphone, and other web enabled devices. Some examples of OTT services are Skype, Google Voice and Viber, which operate and deliver VoIP, messaging and/or video services
OTT terminal application (OTA) is an end user application that is connected to the OTT network and is capable of receiving voice calls using a VoIP technology.
Assume a person wishes to place an international call to Japan. The calling party will dial a number comprising an international call prefix, then the destination country calling code (e.g. 81 for Japan), then (usually) an area code, omitting or suppressing leading zero, then the local telephone number.
The calling party's Telecommunications Service Provider (TSP) now looks for a service provider in Japan that can terminate the call to the number dialed, such as NTT (Nippon Telegraph and Telephone Corporation) or some other telecommunication provider such as AT&T, Orange, O2, Vodafone, BT, France Telecom, or any TSP having business relations with the calling party's TSP and capable of routing the call to the end-point.
It does so by routing the call to the carrier (computer to computer) it has business relations with; the carrier will check whether it can make the call to the specified number. If it can, the call will be routed to the user or to a third party carrier. If it cannot route the call it will reject the call and the calling party's TSP will try the next hop (i.e. a different carrier). This process is done sequentially carrier by carrier.
FIG. 1 is a schematic representation of a prior-art system 100 for a call from one TTA terminal 105 to another TTA terminal 140. The caller's local TSP (TSP1 110) receives the caller's dialed standard TTN number and begins a sequential search of another TTN carrier (e.g. TSP2 120) to terminate the call. If TSP2 rejects the call, TSP1 continues the sequential search until it reaches Non OTT TSPi 130 which is able to terminate the call to the OTA 140.
FIG. 2 is a schematic representation of another prior art system 200 for a call from a TTA terminal 205 to an OTA 230. The caller's local TSP (TSP1 210) receives the caller's dialed OTT number and begins a sequential search of another TTN carrier (e.g. TSP2 220) to terminate the call. If TSP2 rejects the call, TSP1 continues the sequential search until it reaches the end of its available TSPs list. The call cannot be terminated. The reason is that the OTT carrier and the TSP do not share the same user identity (numbering format).
FIG. 3 is a schematic representation of another prior art system 300 for a call from a TTA terminal 305 to an OTA 340. In this configuration the OTA 340 has been allocated a special number for TTN to OTT communication, different than its regular identity. The caller's local TSP (TSP1 310) receives the caller's dialed OTT number and communicates it to an OTT gateway 320. OTT gateway 320 recognizes the dialed number as belonging to OTT TSP 330 and OTT TSP 330 can match the dialed number with an OTT (e.g. Skype) user 340
In order to provide smooth TTA to OTA communication there is need for a call originating from a TTA to terminate seamlessly at an OTA.